To determine if reduction of body temperature to 32 C (88F) (moderate hypothermia) may improve outcome following severe brain injury, In order to determine if hypothermia is effective, we will prospectively randomize patients to receive moderate hypothermia or to be kept normothermic. The patient assigned to receive hypothermia will be cooled within six hours after their severe traumatic brain injury to 88F for a period of 48 hrs, and then rewarmed over 12 hours. There is laboratory data that cooling might be beneficial. Preliminary studies in adult patients with head injuries also have suggested some beneficial effects from hypothermia. Because of this and the finding that cooling patients can be done safely, we believe that it may be of benefit for children with severe head injury.